[U-Boot] Using u-boot to update the kernel and root-file system on NAND chip on imx28evk from USB memory stick

[Bill]

All,

     I'm needing the ability to upgrade the kernel and root-filesystem 
on the NAND chip on the imx28evk from new files that reside on a USB 
memory stick.  That is I want to partition the NAND (mtd) into 3 
sections that contain  u-boot, kernel, rootfs.  Then whenever the system 
is booted, u-boot will probe the USB memory stick (using fatls and 
looking for a  kernel file and rootfs file)  If the files exist on the 
USB memory stick, uboot will automatically (first it will verify a 
CRC/Checksum) erase the kernel and rootfs sections on the NAND chip, and 
then copy the new kernel and rootfs from the USB stick to their 
respective sections in the flash chip (I think using fatload)?.  It will 
never write a new u-boot.

    I've also seen where u-boot can define the NAND flash partitions 
using the mtdparts command and pass these along to the kernel via 
command line args?

    Can u-boot write/erase to a nand partition (i.e. /dev/mtd0) instead 
of using absolute memory addresses?

Thanks,
Bill